Gray Screen/Restart Button Error

OK, I know this sounds funny, but I didn't know what else to call it. Whatever application I'm running, doesn't matter what it is.....

It looks like a tinted window shade comes down from the top of the screen turning it about 50% gray, with a Large "power button" symbol and it tells you that you need to restart your computer either using the forced restart button or holding down the power button on your desktop.

Does anyone know what kind of error this is? Why does it happen? And how do I fix it?

I have run such programs as: Main Menu and ClamXav which was reccomended by members of this forum.

Any suggestions?

Sounds like the kernel panic screen to me, but I dunno what you would do about that... so I'm basically useless, sorry.

I would try reinstalling the latest OS X update again, but using the standalone installer. If that doesn't work and this continues to happen it sounds like you might have some bad RAM, or a program that is seriously screwing things up.

grey screen restart

im getting this exact same problem and have another friend with the same thing aswell..
i tried reinstalling twice and still its doing it.
any other ideas to what this could be??
thanks

Did you install ram at any point? or have a way of testing whether the ram is ok or not?